Linux kernel itself is GPL, so not sure what’s the issue with Guix. Obviously Guix package repository only support libre software, but if you need to use proprietary repository try Guix-nonfree[1].
I am happy Guix and GuixSD exist. Check the gnu Guix mailing list archive both have same roots but are sufficiently different[2].
[1] https://github.com/guix-users/guix-nonfree
[2] https://lists.gnu.org/archive/html/guix-devel/2019-09/msg002...